Lubricant composition



United States Patent ice LUBRICANT COMPOSITION No Drawing. ApplicationNovember 10, 1954, Serial N0. 468,150

3 Claims. (Cl. 25232.7)

2,790,768 Patented Apr. 30, 1957 petroleum compounds, an additiveconsisting essentially of 3 parts by weight of calcium mahoganysulfonate (as a detergent), and 1 part by weight of the zinccycloaliphatic dithiophosphate produced as the zinc salt of the reactionproduct of P285 with methyl cyclohexanol (as an antioxidant andanti-corrosive agent) was found, when added in the amount of 4% byweight, to lower both the flash and fire points of a light base mineraloil by F In other cases, the same additive lowered the flash points ofdiflerent oils anywhere from 25 F. to 40 F. In one case of a heavymineral oil, 4% of the additive was found to reduce the flash point 60F. and

This invention relates to improvements in petroleum compounds, and moreparticularly to raising the flash and fire points of mineral lubricatingoils.

It has been observed that mineral hydrocarbon oils, ordinarily ofreasonably high flash and fire points capable of passing government orindustrial specifications, are materially reduced in such flash and firepoints as much as 15 F. or more by the addition of some types ofadditives. Among additives having this undesirable eflect are basicalkaline earth metal (particularly calcium and barium) mahoganysulfonates of petroleum. Others are zinc and barium hydrocarbondithiophosphates such as zinc and barium alkyl dithiophosphate; e. g.zinc hexyldithiophosphate; and zinc and barium cycloaliphaticdithiophosphates, for example zinc and barium salts of methylcyclohexanol-PzSa reaction product.

Such additives are usually prepared as concentrates in relatively lightfractions of hydrocarbon oils such as light mineral oil, and theresultant concentrate added to the petroleum compound. The reason forthe consequent lowering of the original flash and fire points is notunderstood, but in any case the net result is highly undesirable and mayresult in an oil that is otherwise excellent for a specific purposebeing rejected because of too low a flash or fire point.

An object of this invention is to maintain the flash and fire points ofsuch petroleum compounds despite any lowerin effect of the additive andeven to raise these points in some cases.

Another object of the invention is the provision of a petroleum productcontaining an additive or additives tending to lower the fire and flashpoints thereof, in combination with a compound substantially eflectiveto offset the lowering effect of the additive.

I have discovered that the lowering of the fire and flash points ofmineral oils, as caused by additives referred to above, can besubstantially overcome by the incorporation of relatively small amountsof a liquid dimethyl silicone polymer having the following formula:

in which n is 1 or more. In most cases it is believed that the productcontains a number of such polymers of different chain lengths andperhaps different chain types. Viscosities of 100 centistokes or higherat 25 C. are suitable, for example 100 cs., 1,000 cs. and 100,000 cs.

Good results in raising flash and fire points by 15 F. or more have beenobtained with amounts of the silicone up to 2.5 p. p. m. Above thisfigure the flash and fire points do not increase commensurately with theadditional silicone, thus indicating the criticality of 2.5 p. p. 'm.

Example 1 As an example of the unusual properties of such dimethylsilicone in raising the flash and fire points of the fire point 10 F. Bythe incorporation of only small amounts of dimethyl silicone in theseoils, the entire loss in flash and fire points was recovered in mostcases, and in some cases there was an appreciable gain over the flashand fire points of the oils prior to the addition of the additive.

Specifically, 752 pounds of a mineral oil having a flash point of about475 F., COC, was compounded with 34 pounds of the above additive (4.5%by weight based on the oil), after which its flash point was only 430F., COC. The addition of 2.5 p. p. m. of cs. dimethyl silicone raisedthe flash point to 490 F., COC.

The inclusion of 5 p. p. in. of the same silicone gave no furtherimprovement in flash point, which remained at 490 F., thus showing that2.5 p. p. m. is a critical upper limit.

The dimethyl silicone was prepared as a kerosine concentrate, sufficientkerosine being added to 10 grams of the silicone fluid to bring thetotal volume up to 100 milliliters. The silicone fluid added to thekerosine had a viscosity of 100 cs. at 25 (3., a specific gravity of0.9733, and a silicon content of approximately 35.7% by weight.

The zinc salt was prepared in accordance with the principles describedin U. S. Patent 2,540,084, and had the following structural formula:

wherein R=methy1 cyclohexyl radical.

The calcium mahogany sulfonate had the following structural formula:

wherein the structure of the R groups is uncertain since the product isobtained by sulfonation of heterogeneous petroleum fractions.

All flash and fire tests were made according to ASTM-D92-46 otherwiseknown as U. S. Government method 110.33, the tests also being called theCleveland Open Cup (COC) tests.

This application is a continuation-in-part of my application Serial No.25,511, filed May 6, 1948, now abandoned, and my application Serial No.292,978, filed June 11, 1952, now abandoned.

I claim:

1. A composition of matter consisting essentially of a minerallubricating oil, 4 to 4.5% by weight based on said oil of a mixture ofan alkaline earth metal mahogany sulfonate and a dithiophosphateselected from the group consisting of zinc and barium hexyl and methylcyclohexyl dithiophosphates, said mixture acting to lower the flashpoint of said mineral lubricating oil alone by at least 15 F., and anamount up to 2.5 p. p. m. of a liquid dimethyl silicone polymereffective to raise the flash point of said mineral lubricating oilcontaining said mixture by at least 15 F.

2. A composition of matter consisting essentially of a minerallubricatin oil, 4 to 4.5% by weight based on said oil of a mixture ofcalcium mahogany sulfonate and zinc hydrocarbon dithiophos'phate made asthe zinc salt of the reaction product of P285 with methyl cyclohexanol,said mixture acting to lower the flash point of said mineral lubricatingoil alone by at least 15 F., and an amount up to 2.5 p. p. m. of aliquid dimethyl silicone polymer effective to raise the flash point ofsaid mineral lubricating oil containing said mixture by at least 15 F.

3. A composition of matter consisting essentially of about 752 parts byweight of a mineral lubricating oil, about 34 parts by weight of amixture of 3 parts by weight of calcium mahogany sulfonate and 1 part byweight of zinc hydrocarbon dithiophosphate made as the zinc salt of thereaction product of P255 with methyl cyclohexanol, said mixture actingto lower the flash point of said mineral lubricating oil alone by atleast 15 F., and an amount up to 2.5 p. p. m. of a liquod dimethylsilicone polymer effective to raise the flash point of said minerallubricating oil containing said mixture by at least 15 F.

References Cited in the file of this patent UNITED STATES PATENTS

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A MINERALLUBRICATING OIL, 4 TO 4.5% BY WEIGHT BASED ON SAID OIL OF A MIXTURE OFAN ALKALINE EARTH METAL MAHOGANY SULFONATE AND A DITHIOPHOSPHATESELECTED FROM THE GROUP CONSISTING OF ZINC AND BARIUM HEXYL AND METHYLCYCLOHEXYL DITHIOPHOSPHATES, SAID MIXTURE ACTING TO LOWER THE FLASHPOINT OF SAID MINERAL LUBRICATING OIL ALONE BY AT LEAST 15*F., AND ANAMOUNT UP TO 2.5P.P.M. OF A LIQUID DIMETHYL SILICONE POLYMER EFFECTIVETO RAISE THE FLASH POINT OF SAID MINERAL LUBRICATING OIL CONTAINING SAIDMIXTURE BY AT LEAST 15*F.